Linking photosynthesis and leaf N allocation under future elevated CO2 and climate warming in Eucalyptus globulus
Date
2017
Authors
Sharwood, Robert
Crous, Kristine Y
Whitney, Spencer
Ellsworth, David S
Ghannoum, Oula
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford University Press
Abstract
Leaf-level photosynthetic processes and their environmental dependencies are critical for estimating CO2 uptake from the atmosphere. These estimates use biochemical-based models of photosynthesis that require accurate Rubisco kinetics. We investigated the effects of canopy position, elevated atmospheric CO2 [eC; ambient CO2 (aC)+240 ppm] and elevated air temperature (eT; ambient temperature (aT)+3 °C) on Rubisco content and activity together with the relationship between leaf N and Vcmax (maximal Rubisco carboxylation rate) of 7 m tall, soil-grown Eucalyptus globulus trees. The kinetics of E. globulus and tobacco Rubisco at 25 °C were similar. In vitro estimates of Vcmax derived from measures of E. globulus Rubisco content and kinetics were consistent, although slightly lower, than the in vivo rates extrapolated from gas exchange. In E. globulus, the fraction of N invested in Rubisco was substantially lower than for crop species and varied with treatments. Photosynthetic acclimation of E. globulus leaves to eC was underpinned by reduced leaf N and Rubisco contents; the opposite occurred in response to eT coinciding with growth resumption in spring. Our findings highlight the adaptive capacity of this key forest species to allocate leaf N flexibly to Rubisco and other photosynthetic proteins across differing canopy positions in response to future, warmer and elevated [CO2] climates.
Description
Keywords
Canopy position, elevated CO2 and temperature, Eucalyptus globulus, photosynthesis, Rubisco kinetics, Vcmax, whole-tree chambers
Citation
Collections
Source
Journal of Experimental Botany
Type
Journal article
Book Title
Entity type
Access Statement
Open Access
License Rights
Creative Commons Attribution License
Restricted until
Downloads
File
Description